Others who have seen it please also add your thoughts on why it's R, so Nursing Mother can make a more informed decision about her dd seeing it...
I think it is R mostly because it is an adult movie - meaning, the whole concept and story and such is a fairly heavy, strange, twisting one. Some of it is a little disturbing, in terms of themes and even visually. There is certainly language in it that I wouldn't use around my parents. There's sexuality in the movie and some strong sexuality in particular that's pretty intense (not in a good way). There's some brief nudity but it's not extravagent. Would I take a 15 year old to see it? Actually, that might be a way to go, to see it with her, then you could talk about it? I think it might be okay for a teen who is a more cerebral, thinking, creative kind of kid - does that make sense? Someone who will take the whole and think the wierd questions of it through, talk about it with someone, etc. I think if you go intending to think about it, it is a great movie. If you go intending to be entertained, then it's probably a little too dark and loaded not to be a little disturbing.